Transmission device, reception device, and transmission method

Abstract

According to one embodiment, a transmission device includes an insertion unit, an allocation unit, a division unit, an IFFT unit, a phase rotation unit, and a transmission unit. The phase rotation unit performs a phase rotation to reduce a PAPR characteristic for each block on which inverse fast Fourier transform has been performed. The transmission unit combines transmission signals, on each of which a phase rotation has been performed by the phase rotation unit, and transmits the combined transmission signal to an external device. In addition, the division unit includes a predetermined band and at least one pilot symbol located outside another of end of this predetermined band on an opposite side of the one end into one block.

What is claimed is: 
     
       1. A transmission device comprising:
 an insertion unit that inserts a pilot symbol into a frequency band of a subcarrier of orthogonal frequency division multiplexing (OFDM) at intervals set in advance; 
 an allocation unit that allocates, within the frequency band of the subcarrier, a predetermined band which is a part of this frequency band, modulated in accordance with a transmission signal to be transmitted to an external device set in advance, and has a pilot symbol at one end; 
 a division unit that divides the frequency band of the subcarrier into a plurality of blocks; 
 an IFFT unit that performs inverse fast Fourier transform on each of the blocks; 
 a phase rotation unit that performs a phase rotation to reduce a peak-to-average power ratio (PAPR) characteristic for each of the blocks on which the inverse fast Fourier transform has been performed; and 
 a transmission unit that combines the transmission signals, on each of which the phase rotation has been performed by the phase rotation unit, and transmits the combined transmission signal to the external device, wherein 
 the division unit includes the predetermined band and at least one pilot symbol located outside of another end of the predetermined band on an opposite side of the one end into one block, and sets a greater number of candidate amounts of a phase rotation performed on a first block including the predetermined band among the blocks than candidate amounts of a phase rotation performed on a second block not including the predetermined band among the blocks. 
 
     
     
       2. The device according to  claim 1 , wherein the transmission unit boosts the transmission signal of the predetermined band. 
     
     
       3. A reception device comprising:
 a reception unit that receives a transmission signal of a band out of a frequency band of a subcarrier of orthogonal frequency division multiplexing (OFDM), the band including a predetermined band which is a part of this frequency band, in which a pilot symbol is inserted at one end, and which is included in a block in which a phase rotation is performed to reduce a PAPR characteristic, and including at least one pilot symbol located outside of another end of the predetermined band on an opposite side of the one end; 
 an FFT unit that performs fast Fourier transform on the received transmission signal; 
 an estimation unit that estimates a channel response for the predetermined band on the basis of the pilot symbol included in the transmission signal on which the fast Fourier transform has been performed; and 
 a decoder that decodes the transmission signal using the estimated channel response, wherein 
 candidate amounts of a phase rotation performed on a first block including the predetermined band among the blocks is greater than candidate amounts of a phase rotation performed on a second block not including the predetermined band among the blocks. 
 
     
     
       4. A transmission method comprising:
 inserting a pilot symbol into a frequency band of a subcarrier of orthogonal frequency division multiplexing (OFDM) at intervals set in advance; 
 allocating, within the frequency band of the subcarrier, a predetermined band which is a part of this frequency band, modulated in accordance with a transmission signal to be transmitted to an external device set in advance, and has a pilot symbol at one end; 
 dividing the frequency band of the subcarrier into a plurality of blocks; 
 performing inverse fast Fourier transform on each of the blocks; 
 performing a phase rotation to reduce a PAPR characteristic for each of the blocks on which the inverse fast Fourier transform has been performed; 
 combining the transmission signals, on each of which the phase rotation has been performed, and transmitting the combined transmission signal to the external device; 
 including the predetermined band and at least one pilot symbol located outside of another end of the predetermined band on an opposite side of the one end into one block; and 
 setting a greater number of candidate amounts of a phase rotation performed on a first block including the predetermined band among the blocks than candidate amounts of a phase rotation performed on a second block not including the predetermined band among the blocks.